Holographic

This work presents the theoretieal results and their experimental verifications concerning two possible methods for predicting the material discontinuities shape and severity. The methods are developed for the case of the eddy current transducer with orthogonal coils, for two situations for long crack-tjfpe discontinuities, a metod based on the geometrical diffraction has been used, while in the ease of short discontinuities the holographic method is prefered. 

The holographic image of the discontinuity is reconstructed by means of the relation... 

Figure 5 The modification of intensity of one of the central points of the hole images vs. the distance between the plane of discontinuities and the plane of the holograph...

Accordingly, due to the presence of the maximum for z =d -h, the holographic procedure enables to determine not only shape and location of small discontinuities, but also their subsurface depth. 

The first method, based on the geometric theory of diffiaction, can be used in the case of cracks, while the second - the holographic one, can be used for small discontinuities. The both methods have been developed for the case of an eddy current transducer with orthogonal coils. 

Since ED by a surface is a complicated process, there is no routine method available to directly and accurately extract atomic positions from the experimental data. Direct holographic methods have been proposed [24], but have not yet... 

Saldin D K, Chen X, Vam vakas J A, Ott M, Wedler H, Reuter K, Heinz K and De Andres P L 1997 Holographic LEED a review of recent progress Surf. Rev. Lett A 991-1001... 

Fourkas J T and Payer M D 1992 The transient grating a holographic window to dynamic processes Acc. Chem. Res. 25 227-33... 

Morinaga M, Yasuda M, Kishimoto T and Shimizu F 1996 Holographic manipulation of a cold atomic beam Phys.Rev.Lett. 77 802-5... 

Diffraction gratings may be made by a holographic process, but blaze characteristics cannot be controlled and their efficiency is low in the infrared. They are mostly used for low-order work in the visible and near-ultraviolet. 

Filters, acoustooptic Filters, holographic Filters, metallic Filter types Filtration... 

The last two terms in the transmittance expression enable the holographic reconstmction process. 

Fig. 2. Holographic recording system. S is the object wave and R the plane wave reference.

Fig. 3. Holographic reconstmction. (a) Reconstmction of virtual image of object (b) reconstmction of real image of object.

Holographic information can be recorded by spatially modulating either (or a combination of) the absorption or phase (index or thickness change). 

Display holography is by far the most familiar and weU-developed holographic appHcation to date with several museums dedicated to holographic art. 

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